Collaborative Research: Sediment and Stability: Quantifying the Effect of Moraine Building on Greenland Tidewater Glaciers

The Greenland Ice Sheet (GrIS) is presently the largest contributor of added mass to rising sea levels, recently surpassing contributions from alpine glaciers and ice caps, the Antarctic Ice Sheet and land water storage. Mass loss is concentrated at the periphery of the ice sheet where low-lying outlet glaciers drain into the warm ocean surrounding Greenland. Despite overall mass loss, outlet glaciers of the Greenland Ice Sheet have experienced significant variability in the amount of glacier-front retreat observed over the satellite era. This variability remains unexplained because there are many processes that can influence the position of the front of an outlet glacier and these environments are difficult to obtain observations in. This project aims to collect observations from the front of three outlet glaciers in Greenland where retreat variability has been observed. The goal of this project is to determine if the deposition of sediment at the ice-ocean boundary is responsible for the observed variability in glacier retreat. Further, this project will measure the rates and types of sedimentation processes present at the active glacier front as well as the past position of each glacier observed in the satellite record. The project will also take observations of basic glacier parameters that may be responsible for variations in the rates of sedimentation between glaciers.The overarching goal of this project is to understand the fundamental drivers of ice sheet change and stability through focusing on a poorly understood, observation-limited part of the system: the sediment budget. Moraine building at glacier termini may enable larger steady-state glaciers than would be possible in the absence of sediment, as is evident in high-meltwater settings (e.g., Alaska). However, processes and rates of proglacial sedimentation are poorly known, especially in Greenland, where morainal banks are abundant but where the influence of bank formation on ice sheet dynamics is unconstrained. The central hypothesis of this project is that morainal bank sedimentation can stabilize or delay retreat for some glacier systems. This project will test this hypothesis with observations of four processes that contribute to moraine building at three neighboring Greenland glaciers with sharply different dynamic histories and geometries. The project will deploy a novel remotely operated vehicle (ROV Nereid) designed for surveying and sampling in deep, ice marginal environments to obtain high-resolution geological, geophysical, and oceanographic measurements at the ice-sediment-ocean interface. This project will train graduate students, with a focus on mentorship and diversifying the geosciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

格陵兰冰盖（GRIS）目前是增加海平面上升的质量的最大贡献者，最近超过了高山冰川和冰盖，南极冰盖和陆上水存储的贡献。质量损失集中在冰盖的外围，低洼的出口冰川排入了格陵兰周围温暖的海洋。尽管总体损失了总体损失，但格陵兰冰盖的出口冰川在卫星时代观察到的冰川前撤退量的数量显着差异。这种可变性仍然无法解释，因为有许多过程可以影响出口冰川前部的位置，并且这些环境很难获得观察结果。该项目的目的是从格陵兰岛的三个出口冰川的前沿收集观察结果，并观察到了撤退可变性。该项目的目的是确定在冰山边界上沉积物的沉积是否导致冰川静修中观察到的可变性。此外，该项目将衡量活动冰川前部存在的沉积过程的速率和类型，以及在卫星记录中观察到的每个冰川的过去位置。该项目还将观察基本的冰川参数，这些参数可能导致冰川之间沉积速率的变化。该项目的总体目标是通过专注于熟悉的，观察到的限制性部分来了解冰盖变化和稳定性的基本驱动因素：沉积物预算：沉积物预算。冰川末端的冰ora建筑物可能会使在没有沉积物的情况下实现比在没有沉积物的情况下可能更大的稳态冰川，这在高熔水环境（例如阿拉斯加）中很明显。然而，冰期沉积的过程和速率是鲜为人知的，尤其是在格陵兰岛，那里的莫林银行很丰富，但在库层形成对冰盖动态的影响不受限制。该项目的核心假设是，莫伦银行沉降可以稳定或延迟某些冰川系统的撤退。该项目将通过观察四个过程的观察结果来检验这一假设，这些过程有助于在三个邻近的格陵兰冰川上建造具有急剧不同的动态历史和几何形状的过程。该项目将部署一种新型远程操作的车辆（ROV NEREID），旨在在深层的冰边缘环境中进行测量和采样，以在冰雪界面界面获得高分辨率的地质，地球物理和海洋学测量。该项目将培训研究生，重点关注指导和多元化地球科学。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响审查标准通过评估来获得支持的。